Metallurgical method



March 16, 1937. A. J. QUENEAU METALLURGICAL METHOD Filed Oct. 9, 1955 3 Sheets-Sheet 1 INVENTOR.

Mar 193,7. A. L. J. QUENEAU 2,073,994

ME TALLURG I CAL METHOD Filed Oct. 9, 1935 3 Sheets-Sheet 2 v INVENTOR.

Y %Q 9 fl ATfoRNEKi Mal -ch 16, 1937. A. L. J. QUENE'AU' 2,073',994

' METALLURGICAL METHOD Filed Oct. 9, 1935 1 5 SheetsSheet 3 INVENTOR g I fiaeuarnvlawuzuv QuE/vEAu BY J Patented Mar. 16, 1937 UNITED STATES PATENT OFFICE- 2,073,994 METALLURGICAL METHOD Augustin Leon Jean Queneau, Bernardsville, N. J. Application October 9, 1935,'Serial No. 44,271

4 Claims.

My invention relates to a method 'and apparatus for roasting certain materials such as residues of zinc distilling furnaces for the recuperation of zinc and lead values. The recupera- 5 tion of these values by roasting is very' frequently done by a process known as the Waelz process" various forms and modifications of which are described in the following patents: Nos. 1,618,204, 1,705,128, 1,725,865, 1,728,681, 1,731,898, 1,736,665,

and 1,541,561.

In roasting materials of the above type they are fed admixed with fuel into the upper end of the kiln into which the material to be roasted is fed, drops to such an extent that the material tends to form a ring of slag at a short distance I below the point where it is fed into the kiln. As'

this slag ring increases progressively, it eventually attains a thickness as, for example, after ten to fourteen days operation, sumcient to prevent the feeding of material into the kiln. This slag. formation is apparently, due to a difference in temperature between the material fed into the kiln and the kiln lining at-the point of formation.

In my present invention the formation of a slag ring is avoided and the fed material is rapidly heated, thereby enabling the kiln to be operated for a long or indefinite period of time.

40 In the operation -of kilns of the above type, an

excess of fuel is supplied with the material and is carried to the discharge end of the kiln. The

heating effect attainable by the combustion of this fuel cannot be obtained in methods and appa- 5 ratus heretofore used because it is impossible to supply suficient air through the discharge end of thefurnace to completely burn the fuel withcharging of materials into the kiln to burn the coke or fuel in the charge. An, additional quantity of easily ignitable fuel, such as finely divided bituminous coal, .may be added to the charge. As a result, the highly volatile fuel is ignited and 5 burned upon reaching an ignition temperature and supplies sufiicient heat to heat the charging materials rapidly in the upper part of the kiln. This additional air is supplied near the upper part of the kiln by means of blowers spaced at 10 intervals about the circumference of the kiln and supplying blasts of air through nozzles directly into the kiln. The blowers may be driven by any suitable means as, for example, by electric motors receiving current from, brushes bearing 15 against take-off rings encircling the kiln.

The various features of the invention are illustrated in the accompanying drawings, in which- Fig. his a diagrammatic sketch of a rotary kiln embodying a preferred form of the invention.

Fig. 2 is a cross section of the kiln'taken on line 2-2 of Fig. 1. Fig. 3 is a side view of a portion of the kiln taken on a larger scale than that of Fig.- 1, and rFigs. 4 and 5 are detail sections through the kiln wall taken endwise, respectively, of the blowerand nozzle.

. In the embodiment of the invention shown in the accompanying drawings, charging material is fed through a feeding chute l0 into the upper end of a rotary kiln ll having supporting rings i2 and i3 rotatable on rollers M and I5, respectively, mounted on suitable bases l6 and H. A blast of air is passed upwardly from the lower or discharge end It of the rotary kiln to the charging or upper end it and comes rapidly into contact with the charging material as the'latter passes downwardly to the discharge end while the kiln is rotated. The exhaust gases leaving the upper end of the kiln pass through a flue 20 to waste heat boilers or other heat absorbing apparatus. To maintaina temperature near the feed end sufflcient to prevent the formation of a s'lag ring, a somewhat volatile fuel is supplied with the feed near the feeding chute. ii). To ignite and burn -this fuel, additional quantities of air are blown into the kiln a short distance below the feeding chute it through nozzles 2|, four being shown by way of example, arranged at equal intervals about the circumference of the, kiln. The nozzles, however, are preferably not arranged allin one zone but may also be spaced at longitudinal distances on the kiln. Blasts of air are supplied to the several nozzles 2| by means of blowers 22 mounted on pedestals 23 on the ,kiln and driven by individual motors 2| also mounted on pedestals 25 on the kiln. The motors 24 are driven by current supplied from a main 26 through brushes 2! to collector rings 28 encircling the kiln M and connected by suitable wiring 29 to the motors zt. The electrical connection has been shown as a I three-phase system, but it will be understood that this is merely by way of example and that other arrangements of electric current may be used.

.By using several blowers and airblasts the air supplied near the charging end may be more readily distributed about the kiln. Each blower and nozzle may be provided with a regulating air gate or damper 383 to control the blast of air.

Through the above invention the temperature of the kiln at the charging end may be maintained sufilciently high to rapidly heat the charging material and prevent its becoming partly sintered and cong'ealing on the kiln lining to form a slag ring. The roasting of the ores or residues and the operation of the kiln are thereby greatly facilitated. v i.

What I claim is: p

1. A method which comprises passing a mixture of fuel and zinc containing material countercurrent through a horizontally passing. blast of oxidizing gases while agitating said fuel and material, andinjecting additional air at intervals about said blast near the charging end of said blast.

2. A method which comprises passing a mixture of fuel and zinc containing material countercurrent through a horizontally passing blast of oxidizing gases, agitating said fuel and material while passing through said blast, and injecting additional air into said blast a short distance below the charging end of said material and fuel.

3. A methodof treating zinc containing mineral material to recover zinc therefrom which comprises feeding said material admixed with fuel to the upper end of a slightly inclined rotating cylinder, supplying air for combustion to the 

